Study of NPS1, a novel CDC gene of cerevisiae

NPS 1基因是酿酒酵母细胞分裂周期（CDC）的新基因，编码一个160 kd的细胞生长必需的核蛋白。本研究对NPS 1基因在细胞周期中的功能进行了研究，获得了以下结果：1）构建了一个突变型NPS 1基因，该基因在蛋白激酶consensus基序的ATP结合位点的792位由赖氨酸残基（Lys 792）变为谷氨酸残基，发现Lys 792对NPS 1基因产物的体内功能是不可缺少的。2）通过对只在半乳糖培养基中表达NPS 1基因的条件致死菌株的表型研究，3）NPS 1基因产物定位于酿酒酵母的核小体中，并具有DNA-4）用携带NPS 1基因的重组杆状病毒转化SF 9细胞，成功地表达了NPS 1蛋白。5）为了鉴定与NPS 1相关的基因，我进行了以下实验：i）分离NPS 1基因高剂量表达抑制生长的突变体，ii）筛选NPS 1缺失致死的高拷贝抑制基因，iii）筛选NPS 1缺失致死的高拷贝抑制基因，iv）筛选NPS 1缺失致死的高拷贝抑制基因，iv）筛选NPS 1缺失致死的高拷贝抑制基因，iv）筛选NPS 1缺失致死的高拷贝抑制基因，iv）筛选NPS 1缺失致死的高拷贝抑制基因。（3）通过NPS 1基因的高剂量表达，筛选引起综合致死的基因。通过上述实验获得的突变体和基因的分析正在进行中。

The NPSl gene is a novel cell division cycle (CDC) gene of Saccharomyces cerevisiae enconding a 160 kd nuclear protein essenntial for cell growth. I investigated the functions of NPS1 gene in cell cycle and obtained the following results.1) I constructed a mutant nps1 gene which has a glutamic acid residue at position 792 instead of lysin residue (Lys792) at a suspected ATP-binding site of protein kinase consennsus motief, and found that Lys792 is indispensable for in vivo function of NPS1 gene product.2) By investigating the phenotypes of conditional lethal strain which can express NPS1 gene only in galactose medium, I found that nps1 gene works in g2 phase of S.cerevisiae transducing the signal of completion of DNA replication.3) The NPS1 gene product was found to locate in nuclear saffold of S.cerevisiae and possess DNA-binding activity.4) I succeeded to produce the Nps1 protein in SF9 cell transformed with recombinant baculovirus carrying NPS1 gene. Large scaled culture of transformed SF9 cells and purification of Nps1 protein are now on going.5) In order to identify genes acting in relation to NPS1, I carried out the following experiments : i) isolate mutant whose growth is suppressed by the high dosage-expression of NPS1 gene ; ii) screen the high copy suppressor of lethality caused by NPS1 depletion ; iii) screen the gene which cause synthetic lethality with high-dosage expression of NPS1 gene. The analyzes of mutants and genes obtained by the above experiments are now on going.